<VV> new thread- dual turbo on a corsa

[John Kepler]

----- Original Message ----- 
From: "Peter Robb" <robpe009@student.otago.ac.nz>
To: <virtualvairs@corvair.org>
Sent: Thursday, January 13, 2005 6:02 AM
Subject: <VV> new thread- dual turbo on a corsa


> Hello I am Peter From New Zealand,
>
> I wish to start a new thread.
>
> I have a 65 180 HP Corsa minus its turbo gear. I bought a chrome inlet
> manifold and note its offset that could favor the right hand bank of
> cylinders.

If it's the stock manifold system, YEARS of experience with this unit
indicates no real problems with it.  Just as with aircraft, cars improve
with age as the bugs are progressively worked out.
>
> How would I go getting some aftermarket turbochargers rigged up with
> intercoolers, so theres one for each bank of three cylinders with a
> balance tube between them to compensate for any differences.

First, as preamble, I'm NOT knocking the Corvair Turbo......it was the Corsa
Turbo that planted the seeds of the current shop full of cars back when I
was in High School!  The engines remain a significant milestone in American
automotive design and engineering.  The system is simple, yet effective
within a range.....but it isn't perfect.  I'm only commenting on the
"details", not the larger picture or the mill's well-deserved place in
automotive history.  I'm nit-picking, nothing more!

My only experience with multiple turbo set-ups is in race car engines where
they were universally a PITA!  Lots of nice ponies at the expense of systems
that looked like some drug-induced plumber's nightmare, and that could only
be kept running well because of the constant futzing by 3-4 highly skilled
always PO'ed engine mechanics with a stack of diagnostic computers.   In a
'Vair, I suspect that an intercooled multiple turbo set-up would cost a
small fortune or two to purchase and fab.....and in the end, would likely be
more adept at slagging pistons, valves, and heads than burning up pavement
(the Porsche engines had water-cooled heads!)
>
> I am a novice to all this but I noticed some comment in a reveared
> catalogue that turboed corvairs dont boost until in third or top.

The Corvair Turbo system represents the pinnacle of early 1960's technology!
Turbocharging a production car was brand- new, and the GM engineers were
tip-toeing their way through it.  The Corvair turbo lacks such current
ammenities as waste-gates, re-circ loops, pop-off valves, computerized
engine controls, port fuel injection, and knock sensors.  It was pretty much
a carb, a turbo, and a manifold.  To keep the engine alive without a ton of
non-existant (at the time) gadgetry, the boost levels were VERY mild, and
coupled with the small intake valave diameter, didn't really become much of
an issue until the engine gets to around 3000 rpm.  So no, it's not a
question of the boost not working below 3rd gear, it's just with the
more-or-less designed in throttle lag, it's not all that noticable.  In the
higher gears, the engine stays in the higher rev range long enough for the
boost to become apparent.

> I would expect it is possible to get boost in all gears?

You do!  But with the mild manifold pressures and the small valves, you
simply run through the rev range faster than the throttle lag can be
overcome.  Also, from the dyno the charts I've seen, the 140 actually has
more horsepower "area under the curve" than the 180 Turbo!  The turbo power
curve is quite "peaky", where the 140's is much broader

John